1. Field of the Invention
The present invention relates to solar cell module packages and methods for their preparation, and, more particularly, to an improved solar cell module package having increased resistance to breakage, environmental elements or stress and undesirable leakage currents, and a method for its preparation.
2. Description of Related Art
Solar cell modules commonly include a first or top supporting member, which is preferably transparent to light, such as a glass plate, one or more solar cell elements affixed to one surface of the supporting member, which solar cell element or elements may include a conductive layer, preferably a thin conductive layer, for example a layer of tin oxide, on one surface thereof in contact with the supporting member, with the solar cell elements fabricated onto the thin conductive layer, and finally a second thin conductive layer, preferably a metal layer, such as aluminum, to form a conductive backing to the solar cell. An aluminum plate may be provided as a mounting support for the solar cell module. Such modules, comprised of these solar cell elements, while functional under ideal conditions, deteriorate in less than ideal conditions, for example, in the presence of mechanical or environmental stress, caused by heat and cold, cycling between heat and cold, and moisture, particularly humidity, as solar cell modules are often utilized outdoors and frequently in remote locations in harsh climates.
Various improvements to solar cell modules have been attempted, particularly to improve its electrical properties and its resistance to deterioration from various conditions as noted above. One attempted improvement intended for use in modules having an array of solar cell elements spaced from the top supporting member and from the second or back member, is to encapsulate the array with a potting material which places a compressive load on the array and the back member, as in U.S. Pat. No. 4,170,507. Another proposal is to provide an edge seal and a metal bezel in conjunction with potting material providing the compressive load between a cell array and a spaced back plate, as in U.S. Pat. No. 4,231,807. A third proposal, as set forth in U.S. Pat. No. 4,633,032 is to have the back plate spaced from the solar cell element formed on a glass substrate to define a space, to employ a layer of desiccant positioned on the back plate and facing that space, and to have a frame connecting the glass substrate and the back plate at their peripheral portions.
An improvement to solar cell modules to protect the exposed side of the solar cell elements, i.e. the side opposite its surface in contact with the glass or other first supporting member, is to form a thin covering layer on the exposed side, known as a encapsulant or barrier coating. One such barrier coating, formed from a mixture of a two-component fluorinated polyurethane with a silane compound, is taught in U.S. Pat. No. 4,953,577.
While these attempts have been proposed, none has been fully satisfactory in solving the problems of protecting the module against physical breakage as well as electrical breakdowns. Therefore, there is a need for a solar cell module package which provides increased resistance to mechanical breakage as well as to deterioration in electrical properties due to humidity, heat, cold and cycling between such conditions and due to moisture.